let fs = require('fs');
let user = {
    username: "admin1",
    password: "12345",
};
function reg() {
    let data = fs.readFileSync("./persons.json");
    let arr = JSON.parse(data.toString());
    let tag = false; 
    for(let item of arr){
        if(item.username == user.username && item.password ==user.password){
            tag=true;
            console.log('账号已存在');
        };
    };
    if(tag==false){
        arr.push(user);
        fs.writeFileSync("./persons.json",JSON.stringify(arr));
        console.log('注册成功');
    };
};
reg();